α-Lipoic acid chemistry: the past 70 years

α-Lipoic acid (ALA) is a naturally occurring sulfur-containing fatty acid with high antioxidant activity. It is also used to treat diabetes, nerve pain, weight loss, heart disease, and primary mitochondrial disorders. Moreover, numerous therapeutic agents have been studied for managing other clinical conditions, including for anticancer, anti-HIV, anti-inflammatory, and anti-AD treatments. The medicinal importance of ALA, especially its biologically active form (R-ALA), has attracted considerable attention from synthetic chemists in industrial and academic fields. In this review, we discuss synthetic approaches to ALA and R-ALA over the past 70 years (1952 to the present), which will help medicinal chemists further develop novel routes for their synthesis.